Choose extra large picture thumbnail preview but looks smaller

Windows can show thumbnails smaller than the full tile even in Extra large icons. That is expected behavior for non-square images because Windows keeps the original aspect ratio and pads the rest of the tile instead of stretching the picture.

For images such as 1920×1080, 2K, or 4K in 16:9 format, the thumbnail will often look narrower or smaller inside the square thumbnail area. Windows is responsible for fitting the image into the square space while preserving the image proportions.

Also, Windows thumbnail images are stored in discrete cache sizes, including 32x32, 96x96, 256x256, and 1024x1024. Windows retrieves the next largest cached image and scales it down when needed, rather than scaling images up.

So if the files are PNG or JPEG and are widescreen images, the smaller-looking result is consistent with how Windows thumbnails are designed to display.

References:

• Thumbnail Handlers
• Thumbnail Handler Guidelines